I have a stock Evo 9 wastegate actuator and I recently put an O2 dump on. Driving the car today I noticed what sounded like the wastegate fluttering pretty violently. So I pulled the actuator to attempt to tighten the preload a bit. When I flipped it over I noticed the hole in the picture. Looking at the forge replacement on STM there is a set screw in that hole and the hole on mine is clean and looks drilled. So I was wondering if that hole should be there or if I need to close up the hole? Thanks for the input.

 

That's how it's supposed to be. It's a vent hole for non-pressurized side of the WGA.

As far as the fluttering sound, are you running a 3-port boost controller by any chance?

 

Yes I just swapped back to it with this head rebuild. I thought maybe it might be that but I wasn't sure as the tune hasn't been finished just running a base map, so I was trying to cover all my bases mechanically before I blamed the tune.

 

If you mean you just switched back to a 3-port then that's definitely the sound you're hearing. It's not tune related, it's how the 3-port sounds.

 

^^^^hes right i have external dump and 3 port and i hear that sound.

 

Ok it was jus so violent it was registering as knock so I got a lil worried but I'll just trust you guys since I've never had eitheron a car before.

 

I had that fluttering racket when I installed the 3 port "interrupt" style like 95% of users install them but when I did a "bleed" style routing, the flutter is gone and everything in the boost curve is smooth and consistent.